Mineral material such as rock is gained from the earth for processing by exploding or excavating. Rock can also be natural and gravel or construction waste. Mobile crushers and stationary crushing applications are used in the crushing. An excavator or wheeled loader loads the material to be crushed into a feed hopper of the crusher or the processing plant from where the material to be crushed may drop in a jaw of the crusher or a feeder feeds the rock material towards the crusher. The mineral material to be crushed can also be recyclable material such as concrete, bricks or asphalt.
A jaw crusher 100 according to prior art is shown in FIG. 1a. Jaw crushers are suitable, for example, coarse crushing in quarries or crushing of construction material. According to the function principle of the jaw crusher the crushing takes place against jaws, the so called fixed and movable jaws. The body of the jaw crusher is formed of a front end 101 and a rear end 101′ and side plates. The fixed jaw 102 is fixed to the front end of the jaw crusher which fixed jaw is receiving the crushing forces. The movable jaw 103 is fixed to a pitman, the eccentric movement of which movable jaw is generated by rotating an eccentric shaft. The jaw crusher also comprises a belt wheel 104, V-belts 107, a motor 105 and belt wheel 106 of the motor for moving the movable jaw 103. The rock material is crushed between the jaws and is conveyed after the crushing for instance along a belt conveyor to further processing. The crusher also comprises two-part fixing means 110, 110′ for fixing the crusher 100 to frame structures 121 of the processing plant.
The jaw crusher is isolated notoriously from the frame by means of dampers and rubber stoppers. A prior art two-part fixing means 110 is shown in FIG. 1b comprising a fixing piece 111 with for example L-profile form which is fixed (welding or bolt joint) to the crusher, the fixing piece having a bottom surface and two side surfaces, the one side surface in longitudinal direction and the other side surface in cross direction of the machine. The fixing piece also comprises an angle piece 112 with for example L-profile form which is fixed to the frame 121 of the processing plant, a so called end stopper which is preventing the movement of the crusher in machine direction, that is the longitudinal movement. Rubber stoppers 115, 115′ to be pre-tightened with screws are increasing longitudinal rigidity.
There is preferably a material layer 113 of elastic material such as rubber between the bottom surface of the fixing piece 111 and an upper surface of the frame 121 of the processing plant, the object of the material layer being damping forces machine direction influencing the crusher for example caused by impacts of stones. The side surface of the fixing piece 111 which is perpendicular to the longitudal direction and the corresponding side surface of the angle piece 112 which is perpendicular to the longitudal direction are located at a distance from each other and fixed to each other by a bolt joint 114 such that there are rubber stoppers 115, 115′ between the fixing and angle pieces and the bolt joint.
Crushing forces and the material which is dropping in the jaw of the crusher are causing loads to the crusher which are lead to the surrounding structures via the body of the crusher. The dropping of a large stone in the jaw and the crushing of the stone may cause so heavy forces in the machine direction that this may result to damages of the stopper fixings.
In case of a movable, particularly track based, processing plant the fixing means are under even heavier stress. For example, when the crushing plant is moving on an uneven terrain there are caused forces which are straining the frame structures of the processing plant. Forces caused by momentary torsions of the frame of the processing plant are straining the fixing means 110, 110′ because the jaw crusher itself is a rigid and inflexible body and, therefore does not necessarily bend like the frame of the processing plant. In a worst case the crushing plant may be in a cross-supported state due to the unevenness of the terrain wherein the frame of the crushing plant is bent downwards at crosswise located corners. Then, heavy vertical stresses are caused to the fixing means in said corners which may also lead to damages of for example bolts, damping rubbers or welding seams of supports.
The current support of the jaw crusher with the stoppers is not very cost effective solution. The two-part fixing means comprises several parts of which some are also very heavy which is increasing the manufacture and mounting costs thereof.
Because of the excessive vibration one has been driven with the jaw crushers to more rigid rubber dampers and stoppers below the resonance frequency to an amplification area where the ratio of impulse to natural frequency is lower than 1. The excessive vibration damages guard plates, fuel tanks and railings of the maintenance bridges. The vibration is also detrimental for electric components and the motor. Mounting of the damper stoppers is inconvenient and time consuming. There have often occurred problems with the pre-tightening of the screws. If the stoppers are not well pre-tightened the total spring constant in longitudinal machine direction is substantially smaller and one is near the resonance.
An object of the invention is to provide a crushing plant and a support structure of the crusher by which problems associated with the prior art may be avoided or at least minimized.